The present exemplary embodiments relate to the expeditious removal of exudates from a wound site and the concurrent or subsequent delivery of pure oxygen to the Wound site to promote healing of venous stasis and diabetic foot ulcers and other wounds.
Accumulation of wound exudate increases patient discomfort and the potential for bacterial infection, and, thereby, affects adversely the healing process. In particular, chronic wound fluid blocks the proliferation and activity of fibroblasts and keratinocytes. In addition, it prevents easy reach of pure oxygen to the wound bed due to poor oxygen solubility in aqueous fluids, and, hence, the effectiveness of topical intermittent and transdermal sustained oxygen therapies. Chronic wounds are often heavily colonized with bacterial organisms and, therefore, timely removal of exudate is essential to minimize bio-burden. Wound cleansing removes contaminants from the wound surface and renders the wound less conducive to microbial growth. Wounds with foul smelling drainage are generally infected or filled with necrotic debris, and healing time is prolonged as tissue destruction progresses. The fluid of wound edema contains proteolytic enzymes, bacterial toxins, prostaglandins, and necrotic debris, all of which contribute to prolonged chronic inflammation.
Various types of wound dressings and drainage devices have been reported in the patent literature. Thus, a multi-purpose wound dressing is described by Ewall, in U.S. Pat. No. 5,607,388. This patent teaches the use of a multiple layer wound dressing with sequentially removable layers that can be used to control the accumulation of exudate.
A general purpose surgical drain is described in U.S. Pat. No. 3,753,439. This device is a drainage conduit packed inside with soft, non-friable absorbent material. A suction line can be connected to the top of the fixture to drain the exudate.
Argenta and Morykwas (U.S. Pat. Nos. 5,636,643 and 5,645,081) patented a method of treating tissue damage by applying a negative pressure to a wound sufficient in time and magnitude to promote tissue migration and thus facilitate wound closure. Negative pressures in the range of 2-7 inches of Hg are applied over the wound and the surrounding areas. The area around most wounds becomes swollen with intercellular fluid, which is not removed due to insufficient blood circulation, and further compromises blood circulation as time progresses. Application of vacuum over the wound and surrounding area forces the intercellular fluid to flow towards the negative pressure region. Since the wound is open and perhaps sees the most negative pressure, all the intercellular fluid ends up accumulating in the wound. A tube properly placed in the wound and connected to the external vacuum source removes the liquid as it accumulates. Application of negative pressure over the wound site enhances both blood circulation and tissue migration.
The present embodiments herein described differ substantially from that of Argenta and Morykwas in at least two important respects: first, it simply allows better access of oxygen to the tissue bed by removing the naturally secreted wound exudates, and, second, it does not produce a negative pressure directly at a wound site, unlike the Argenta and Morykwas device. It therefore does not induce gross fluid flow from the wound area (from the surrounding tissue bed) or migration of epithelial and/or subcutaneous tissue toward the wound. Any reduced pressure at the wound site is generally less than that experienced in the Argenta and Morykwas device.
Sustained oxygen delivery has been suggested (see, e.g., U.S. Pat. No. 5,578,022) as an effective tool to accelerate the healing process even in the case of chronic wounds. In order to realize the benefits of delivered oxygen, it is important that the access to the tissue bed by oxygen be uninhibited. Exudate accumulation normally prevents such easy access of oxygen to the tissue bed. The present embodiments relate to electrochemical, light-weight devices, capable of both removing exudates from the wound bed, and also of delivering oxygen to the wound. These devices use no mechanical pumps or compressed gases and can be directly attached to the affected limb/area allowing the patient to be ambulatory.